The Sway compiler supports a list of intrinsics that perform various low level operations that are useful for building libraries. Compiler intrinsics should rarely be used but are preferred over asm blocks because they are type-checked and are safer overall. Below is a list of all available compiler intrinsics:
__size_of_val<T>(val: T) -> u64 Description: Return the size of type T in bytes.
Constraints: None.
__size_of<T>() -> u64 Description: Return the size of type T in bytes.
Constraints: None.
__size_of_str_array<T>() -> u64 Description: Return the size of type T in bytes. This intrinsic differs from __size_of in the case of "string arrays" where the actual length in bytes of the string is returned without padding the byte size to the next word alignment. When T is not a "string array" 0 is returned.
Constraints: None.
__assert_is_str_array<T>() Description: Throws a compile error if type T is not a "string array".
Constraints: None.
__to_str_array(s: str) -> str[N]Description: Converts a "string slice" to "string array" at compile time. Parameter "s" must be a string literal.
Constraints: None.
__is_reference_type<T>() -> bool Description: Returns true if T is a reference type and false otherwise.
Constraints: None.
__is_str_array<T>() -> bool Description: Returns true if T is a string array and false otherwise.
Constraints: None.
__eq<T>(lhs: T, rhs: T) -> bool Description: Returns whether lhs and rhs are equal.
Constraints: T is bool, u8, u16, u32, u64, u256, b256 or raw_ptr.
__gt<T>(lhs: T, rhs: T) -> bool Description: Returns whether lhs is greater than rhs.
Constraints: T is u8, u16, u32, u64, u256, b256.
__lt<T>(lhs: T, rhs: T) -> bool Description: Returns whether lhs is less than rhs.
Constraints: T is u8, u16, u32, u64, u256, b256.
__gtf<T>(index: u64, tx_field_id: u64) -> T Description: Returns transaction field with ID tx_field_id at index index, if applicable. This is a wrapper around FuelVM's gtf instruction . The resulting field is cast to T.
Constraints: None.
__addr_of<T>(val: T) -> raw_ptr Description: Returns the address in memory where val is stored.
Constraints: T is a reference type.
__state_load_word(key: b256) -> u64 Description: Reads and returns a single word from storage at key key.
Constraints: None.
__state_load_quad(key: b256, ptr: raw_ptr, slots: u64) -> bool Description: Reads slots number of slots (b256 each) from storage starting at key key and stores them in memory starting at address ptr. Returns a Boolean describing whether all the storage slots were previously set.
Constraints: None.
__state_store_word(key: b256, val: u64) -> bool Description: Stores a single word val into storage at key key. Returns a Boolean describing whether the store slot was previously set.
Constraints: None.
__state_store_quad(key: b256, ptr: raw_ptr, slots: u64) -> bool Description: Stores slots number of slots (b256 each) starting at address ptr in memory into storage starting at key key. Returns a Boolean describing whether the first storage slot was previously set.
Constraints: None.
__log<T>(val: T) where T: AbiEncode Description: Logs value val.
Constraints:
T must implement AbiEncode __add<T>(lhs: T, rhs: T) -> T Description: Adds lhs and rhs and returns the result.
Constraints: T is an integer type, i.e. u8, u16, u32, u64, u256.
__sub<T>(lhs: T, rhs: T) -> T Description: Subtracts rhs from lhs.
Constraints: T is an integer type, i.e. u8, u16, u32, u64, u256.
__mul<T>(lhs: T, rhs: T) -> T Description: Multiplies lhs by rhs.
Constraints: T is an integer type, i.e. u8, u16, u32, u64, u256.
__div<T>(lhs: T, rhs: T) -> T Description: Divides lhs by rhs.
Constraints: T is an integer type, i.e. u8, u16, u32, u64, u256.
__and<T>(lhs: T, rhs: T) -> T Description: Bitwise AND lhs and rhs.
Constraints: T is an integer type, i.e. u8, u16, u32, u64, u256, b256.
__or<T>(lhs: T, rhs: T) -> T Description: Bitwise OR lhs and rhs.
Constraints: T is an integer type, i.e. u8, u16, u32, u64, u256, b256.
__xor<T>(lhs: T, rhs: T) -> T Description: Bitwise XOR lhs and rhs.
Constraints: T is an integer type, i.e. u8, u16, u32, u64, u256, b256.
__mod<T>(lhs: T, rhs: T) -> T Description: Modulo of lhs by rhs.
Constraints: T is an integer type, i.e. u8, u16, u32, u64, u256.
__rsh<T>(lhs: T, rhs: u64) -> T Description: Logical right shift of lhs by rhs.
Constraints: T is an integer type, i.e. u8, u16, u32, u64, u256, b256.
__lsh<T>(lhs: T, rhs: u64) -> T Description: Logical left shift of lhs by rhs.
Constraints: T is an integer type, i.e. u8, u16, u32, u64, u256, b256.
__revert(code: u64) Description: Reverts with error code code.
Constraints: None.
__ptr_add(ptr: raw_ptr, offset: u64) Description: Adds offset to the raw value of pointer ptr.
Constraints: None.
__ptr_sub(ptr: raw_ptr, offset: u64) Description: Subtracts offset to the raw value of pointer ptr.
Constraints: None.
__smo<T>(recipient: b256, data: T, coins: u64) Description: Sends a message data of arbitrary type T and coins amount of the base asset to address recipient.
Constraints: None.
__not(op: T) -> T Description: Bitwise NOT of op
Constraints: T is an integer type, i.e. u8, u16, u32, u64, u256, b256.
__jmp_mem() Description: Jumps to MEM[$hp].
Constraints: None.
__slice<T>(item: &[T; N], start: u64, end: u64) -> &[T]
__slice<T>(item: &[T], start: u64, end: u64) -> &[T]
__slice<T>(item: &mut [T; N], start: u64, end: u64) -> &mut [T]
__slice<T>(item: &mut [T], start: u64, end: u64) -> &mut [T]Description: Slices an array or another slice.
This intrinsic returns a reference to a slice containing the range of elements inside item.
The mutability of reference is defined by the first parameter mutability.
Runtime bound checks are not generated, and must be done manually when and where appropriated. Compile time bound checks are done when possible.
Constraints:
item is an array or a slice; start is a literal, it must be smaller than item length; end is a literal, it must be smaller than or equal to item length; end must be greater than or equal to start __elem_at<T>(item: &[T; N], index: u64) -> &T
__elem_at<T>(item: &[T], index: u64) -> &T
__elem_at<T>(item: &mut [T; N], index: u64) -> &mut T
__elem_at<T>(item: &mut [T], index: u64) -> &mut TDescription: Returns a reference to the indexed element. The mutability of reference is defined by the first parameter mutability.
Runtime bound checks are not generated, and must be done manually when and where appropriated. Compile time bound checks are done when possible.
Constraints:
item is a reference to an array or a reference to a slice; index is a literal, it must be smaller than item length; __dbg<T>(value: T) -> T where T: Debug Description: Automatically calls the Debug trait on the passed value, with file, line and column information. The passed value is returned without any modification, allowing __dbg(...) to be used inside of any expression.
The code generated by this intrinsic function varies with the compilation mode. For example:
forc build <- will print everything as expected
forc build --release <- nothing will be printed To enable code generation even on Release builds, the flag force-dbg-in-release needs to be enabled inside forc.toml.
Example:
[project]
authors = ["Fuel Labs <[email protected]>"]
license = "Apache-2.0"
entry = "main.sw"
name = "some-project"
force-dbg-in-release = trueIt is strongly suggested to always remove this flag before publishing binaries as it will not have any effect when running on real nodes and it only increases gas usage.
Constraints:
T must implement Debug